poj2387 最短路

题意：给出一堆双向路，求从N点到1点的最短路径，最裸的最短路径，建完边之后直接跑dij或者spfa就行

dij：

 #include<stdio.h>
 #include<string.h>
 #include<queue>
 #include<algorithm>
 #include<vector>
 using namespace std;
 typedef pair<int,int> pii;
 const int INF=0x3f3f3f3f;

 int head[],dist[],point[],val[],next[],size;

 void add(int a,int b,int v){
     int i;
     for(i=head[a];~i;i=next[i]){
         if(point[i]==b){
             if(val[i]>v)val[i]=v;
             return;
         }
     }
     point[size]=b;
     val[size]=v;
     next[size]=head[a];
     head[a]=size++;
 }

 struct cmp{
     bool operator()(pii a,pii b){
         return a.first>b.first;
     }
 };

 void dij(int s){
     int i;
     priority_queue<pii,vector<pii>,cmp>q;
     q.push(make_pair(,s));
     memset(dist,-,sizeof(dist));
     dist[s]=;
     while(!q.empty()){
         pii p=q.top();
         q.pop();
         if(p.first>dist[p.second])continue;
         for(i=head[p.second];~i;i=next[i]){
             int j=point[i];
             if(dist[j]==-||dist[j]>p.first+val[i]){
                 dist[j]=p.first+val[i];
                 q.push(make_pair(dist[j],j));
             }
         }
     }
     printf("%d\n",dist[]);
 }

 int main(){
     int t,n;
     while(scanf("%d%d",&t,&n)!=EOF){
         int i,j;
         size=;
         memset(head,-,sizeof(head));
         for(i=;i<=t;i++){
             int a,b,v;
             scanf("%d%d%d",&a,&b,&v);
             add(a,b,v);
             add(b,a,v);
         }
         dij(n);
     }
     return ;
 }

dij

spfa：

 #include<stdio.h>
 #include<string.h>
 #include<queue>
 using namespace std;

 int head[],dist[],next[],point[],val[],size;
 bool vis[];

 void add(int a,int b,int v){
     int i;
     for(i=head[a];~i;i=next[i]){
         if(point[i]==b){
             if(val[i]>v)val[i]=v;
             return;
         }
     }
     point[size]=b;
     val[size]=v;
     next[size]=head[a];
     head[a]=size++;
 }

 void spfa(int s,int p){
     memset(vis,,sizeof(vis));
     memset(dist,-,sizeof(dist));
     queue<int>q;
     vis[s]=;
     dist[s]=;
     q.push(s);
     while(!q.empty()){
         int i,t=q.front();
         vis[t]=;
         q.pop();
         for(i=head[t];~i;i=next[i]){
             int j=point[i];
             if(dist[j]==-||dist[j]>dist[t]+val[i]){
                 dist[j]=dist[t]+val[i];
                 if(!vis[j]){
                     q.push(j);
                     vis[j]=;
                 }
             }
         }
     }
     printf("%d\n",dist[p]);
 }

 int main(){
     int t,n;
     while(scanf("%d%d",&t,&n)!=EOF){
         int i,j;
         memset(head,-,sizeof(head));
         size=;
         for(i=;i<=t;i++){
             int a,b,v;
             scanf("%d%d%d",&a,&b,&v);
             add(a,b,v);
             add(b,a,v);
         }
         spfa(n,);
     }
     return ;
 }

spfa